Mandrels

ABSTRACT

A mandrel assembly according to the present disclosure comprises a plurality of first mandrel segments adapted to form a substantially cylindrical body, a plurality of second mandrel segments adapted to form a portion of a first hemisphere, and a plurality of third mandrel segments adapted to form a portion of second hemisphere. Clamp means are provided to clamp the mandrel segments together to form the completed mandrel. A shaft is disposed through a center aperture in each of the hemispherical portions in such a manner that the mandrel segments forming the hemispherical portions at each end of the mandrel may be attached to the shaft. Fittings, to be integral with the completed container, are attached to the shaft and are adapted to support filament windings. At one end, the fitting is attached to the mechanism utilized to attach the mandrel segments to the shaft. At the opposite end, the fitting is attached to a support means which in turn is locked against a shoulder of the shaft by means of a threaded fastener.

ilnit Setnils ttes te [73] Assignee: The United States of America as represented by the Secretary of the Air Force 122 Filed: Nov. 26, 1969 121 Appl.No.: 870,572

[56] References Cited UNITED STATES PATENTS 3,357,875 12/1967 Corbin,.lr ..l56/425 3,367,815 2/1968 Ragettlietal ..l56/446X Primary Examiner-George F. Mautz Attorney-Harry A. Herbert, Jr.

[57] ABSTRACT A mandrel assembly according to the present disclosure comprises a plurality of first mandrel segments adapted to form a substantially cylindrical body, a plurality of second mandrel segments adapted to form a portion of a first hemisphere, and a plurality of third mandrel segments adapted to form a portion of second hemisphere. Clamp means are provided to clamp the mandrel segments together to form the completed mandrel. A shaft is disposed through a center aperture in each of the hemispherical portions in such a manner that the mandrel segments forming the hemispherical portions at each end of the mandrel may be attached to the shaft. Fittings, to be integral with the completed container, are attached to the shaft and are adapted to support filament windings. At one end, the fitting is attached to the mechanism utilized to attach the mandrel segments to the shaft. At the opposite end, the fitting is attached to a support means which in turn is locked against a shoulder of the shaft by means of a threaded fastener.

n Claims, Drawing Figures PATENTEUMARN I972 SHEET 1 OF 2 INVENTOR. HARRY A. SET/WK MANDREILS This invention relates to mandrels, and particularly to breakdown mandrels for use in constructing filament-wound containers.

F ilament-wound containers and tanks are particularly useful in rocket applications for containing fuel because of their relatively lighter weight as compared to conventional machined tanks and because filament-wound tanks are structurally stronger than metal tanks. One problem associated in the construction of filament-wound tanks on a commercial basis has resided in the fact that it has been difficult to control the dimensional sizes of the mandrel necessary for winding such tank, and therefore it has been difficult to reproduce the tanks accurately.

It is an object of the present invention to provide a mandrel for use in constructing filament-wound containers or tanks which is not subject to varying dimensions.

Another object of the present invention is to provide a mandrel capable of reproducing dimensional stable chambers.

In accordance with the present invention, a breakdown mandrel is provided for use in constructing filament-wound tanks or containers wherein the dimensions of the tank are accurately controlled. Lock means is provided for preventing changes in the dimensions of the mandrel.

According to one feature of the invention, the mandrel comprises a plurality of segments which may be fastened together to form a substantially cylindrical mandrel. The ends of the mandrel are connected to a boss and locked in place against a shoulder to prevent variations in the axial dimension of the mandrel.

When a substantially cylindrical mandrel is relatively rotated with respect to a winding head (by winding the head around the mandrel or by rotating the mandrel about its axis with respect to the head) filament rovings are guided onto the mandrel in accordance with the position of the winding head. A ring fitting is attached to the mandrel so that the filament rovings bond the fitting into the container. I-Ieretofore, when winding was completed, there is a tendancy for some of the filament rovings to shift position or snap back to change the physical dimensions of the container along the axis of the mandrel. A mandrel according to this invention controls snap back by fixing one end of the mandrel to the shaft forming the axis of the mandrel and locking the opposite end of the mandrel against a shoulder. The resulting mandrel assembly is useful in constructing dimensionally controlled containers which may be reproduced without significant dimensional variations.

The above and other features of this invention will be more fully understood from the following detailed description and the accompanying drawings, in which:

FIG. 1 is a partial side view elevation in cutaway cross section of a mandrel assembly in accordance with the presently preferred embodiment of the present invention;

FIG. 2 is a partial section view of the mandrel assembly illustrated in FIG. 1 taken at line 2-2 of FIG. 1;

FIG. 3 is a partial section view of the mandrel assembly illustrated in FIGS. 1 and 2 taken at line 3-3 in FIG. 1; and

FIG. 4 is an exploded view of the portion of the mandrel indicated at region 44 in FIG. 1.

Referring to the drawings, there is illustrated a mandrel assembly in accordance with the presently preferred embodiment of the present invention. The mandrel assembly comprises a plurality of substantially arcuate rectangular segments fastened together by means of lock clamps 11. As illustrated particularly in FIGS. 2 and 3, segments 10 have a slightly arcuate configuration so that when segments 10 are fastened together by clamps 11 they together form a cylindrical body having a central axis 12. Segments 10 have radially disposed lips 13 and 14, lip 13 being adapted to abut lip 14 of the next segment. Both lips 13 and 14 include a key slot adapted to contain key 15 (FIGS. 1 and 3) which is disposed substantially parallel to axis 12 below the inner surface formed by lips 13 and 14. Hence, with the segments 10 clamped together by clamps 11 against lips 13 and 14 and with keys l5 in the respective key slots, relative movement between segments 10 is prevented.

Arcuate segments 16 are clamped to rectangular segments 10 by means of clamps l7, and are clamped together by means of clamps 18. By way of example, clamps 17 may be hinged at pin 20 to segments 16 and are adapted to pull lip 19 of segments 10 toward hinge 20. Clamp 18 is adapted to clamp between lips 21 and 22 of successive segments 16. Preferably, key 23 is disposed in suitable key slots between lips 21 and 22 of segments 16, the key 14 being disposed in a position substantially normal to the inner surface formed by lips 21 and 22. When fastened together segments 16 form a semi-sphere which closes one end of the cylindrical body formed by segments 10. Preferably annular shoulder 75 fits in annular recess 76 to assure proper assembly of segments 10 and 16.

Arcuate segments 16 are fastened, by way of example, by means of suitable threaded fasteners 24 to ring 25 which in turn is threadably fastened by means of fasteners 26 to ring 27. Ring 27 is fixedly attached to shaft 28. By way of example, ring 27 may be welded to shaft 28. Preferably, ring 29 is fastened to ring 30 by fasteners 31, ring 30 being on the outside of the body fastened to ring 25 by fasteners 32. Ring 29 provides a transition or end element for the container to be wound. By way of .example, ring 29 may be a suitable ring fastener or valve housing for use with the completed container.

Arcuate segments 33 are clamped to segments 10 by means of clamps 34. By way of example, clamps 34 may be hinged by hinge 36 to segments 33 and be adapted to bear against lips of segments 10. Each arcuate segment 33 has opposite lips 37 and 38 so arranged that lip 37 of one segment abuts lip 38 of a contiguous segment. Abutting lips 37 and 38 are clamped together by means of clamps 39. Preferably, as illustrated in FIGS. 1 and 2, keys 40 are fitted in suitable key slots between lips 37 and 38 to fix the relative positions of segments 33 to prevent relative movement between segments 33. Keys 40 are preferably disposed normal to the surface formed by lips 37 and 38. Annular shoulder 77 of segments 33 fits in annular recess 78 to assure proper assembly of segments 33 to segments l0. Segments 33 together form a semi-spherical surface closing the end of the cylindrical body formed by segments 10.

The segments 33 are fastened to shaft 28 by the apparatus illustrated in greater detail in FIG. 4, and reference to FIGS. 1 and 4 may be had for specific details of fastening.

Arcuate segments 33 are fastened to ring 41 by means of threaded fasteners 42. Ring 43 is wedged between ring 41 and segment 33 to clamp the rings 41 and 43 between the head of fastener 42 and segment 33. Shaft 28 extends through ring 43 and includes a suitable key slot 44 disposed therein. Key 45 is fitted in key slot 44 and in a key slot in ring 43 so as to prevent relative rotation between ring 43 and shaft 28. Housing 46 is fitted within bore 47 of shaft 28, and pin 48 is passed through aperture 49 of shaft 28, and housing 46 to fasten the assembly together and to lock the relative axial position of housing 46 and shaft 28. A second pin 50 may be provided through the same parts to add to the strength of the assembly and to further prevent movement between the parts. Preferably, pin 50 is normal to pin 48.

Ring 51 is fixedly attached to housing 46 and includes a lip 52 adapted to receive annular portion 53 of ring 54 between lip 52 and housing 46. Portion 53 of ring 54 is adapted to abut shoulder 55 of housing 46 and shoulder 56 of ring 51. Housing 46 includes a threaded portion 57 to which fastener 58 is attached to wedge ring 54 between fastener 58 and the shoulder formed by shoulders 55 and 56. Key 65 is fitted within key slot 66 in housing 46 and in key slot 67 in ring 54 to prevent relative rotation between the housing 46 and ring 54.

Fasteners 59 attach ring to ring 54. By way of example, ring 60 may comprise a suitable ring housing forming an aperture for the completed container formed by the mandrel. Ring 60 is adapted to be positioned over the outer portion of the aperture formed by the mandrel segments 33 when assembled together.

Hub 61 is threadably attached to housing 46 by means of fasteners 62. Hub 61 is threadably assembled by means of fasteners 63 to shaft 64 which in turn is adapted to be rotated by means ofa suitable motor (not shown).

At the other end of the mandrel, plate 68 may be mounted to shaft 28 by fasteners 69 (FIG. 1), the plate being attached to hub 70 by a fastener 71.

In assembly of the mandrel illustrated in the drawings, housing 46 is assembled into bore 47 of shaft 28, and ring 43 is attached over the shaft. Pins 48 and 50 lock the assemblage together, and key 45 is inserted into place to prevent relative rotation of ring 43 with respect to shaft 28. Pins 48 and 50 prevent relative rotation of housing 46 with respect to the shaft. Arcuate mandrel segments 33 are fastened to ring 43 by means of fasteners 42 and are clamped together by means of clamps 39. Keys 40 are attached within the key slots between lips 38 and 37 to prevent relative movement between the segments 33. Fitting 60, which may, for example, be a suitable aperture housing for the completed tank, is fastened by means of fasteners 59 to ring 54. Ring 54 is assembled over housing 46 and portion 53 of ring 54 is brought into abutment against shoulder 55, 56 formed by housing 46 and ring 51. Key 65 is inserted in the key slot 66, 67 to prevent relative rotation of ring 54 with respect to housing 46, and threaded fastener 58 is threaded onto threaded portion 57 of housing 46 to clamp ring 54 between fastener 58 and shoulder 55, 56. Hub 61 is attached by means of fastener 62 to housing 46.

Segments are clamped by means of clamps 34 to segments 33 and are clamped together by means of clamps 11. Prior to attaching each successive segment 10 together, pins are inserted in the pin slots between lips 13 and 14 to prevent relative motion between the respective segments 10.

Segments 16 are attached to segments 10 by means of clamps 17 and are attached together by means of clamps 18. Pins 23 are inserted in the key slots between lips 22 and 21, and the upper portion of segments 16 are fastened by means of fasteners 24 to ring 25. Ring 25 is thereafter attached to ring 27 (which of course if fixedly attached to shaft 28) by means of fasteners 26. Fitting 29 (which may, for example, be a suitable aperture housing fitting for the completed container) is fastened to ring 30 by fasteners 31, ring 30 being fastened by means of fasteners 32 to ring 25.

Shaft 28 may be fastened to hub 70 at one end and to shaft 64 at the other end.

In use of the mandrel in accordance with the present invention, the payoff head for directing filament roving onto the mandrel is rotated relative to the mandrel. For example, the payoff head may be rotated around the mandrel or the mandrel may be rotated about its own axis. The payoffhead guides filament rovings onto the mandrel formed by segments 33, 10 and 16 to form a layer 72 of filament material on the mandrel. Ring fitting 60 and 29 at each end of the mandrel support the rovings in the vicinity of apertures being formed at each end of the container. Since fittings 60 and 29 are fixed relative to the position of the shaft (which of course fixes the positions of each of the mandrel segments) the filament rovings are unable to move or snap back during curing of the resin associated with the filament roving. By fixing the position of ring 54 (which of course carries ring 60) against shoulder 55, 56 relative movement axial movement of the ring with respect to the mandrel is prevented.

The mandrel in accordance with the present invention is particularly useful for constructing storage containers for storing fuels for rockets which normally have a corrosive effect on metal containers. The containers may be of any size, and the mandrel has proven effective for constructing containers having a length of about 67 inches and a diameter of about 52 inches. Such mandrels have been found to have a gap between mandrel parts no greater than about 0.005 inches. For such a mandrel, it has been found that nineteen of each type mandrel segment is satisfactory for constructing the mandrel. The mandrel segments, together, form a smooth, cylindrical surface having hemispherical end portions This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation.

What is claimed is:

1. A mandrel assembly for supporting filament material for constructing a container, said assembly comprising: a plurality of first mandrel segments each having a surface forming a portion of a substantially cylindrical body; first fastener means for fastening said first mandrel segments together to form a substantially cylindrical body; a plurality of second mandrel segments each having a surface forming a portion of a substantially hemispherical body; second fastener means for fastening said second mandrel segments together to form a first substantially hemispherical body; a plurality of third mandrel segments each having a surface forming a portion of a substantially hemispherical body; third fastener means for fastening said third mandrel segments together to form a second substantially hemispherical body; fourth fastener means for fastening said first hemispherical body to said cylindrical body; fifth fastener means for fastening said second hemispherical body to said cylindrical body; first and second apertures formed in said first and second hemispherical bodies, respectively, said apertures being coincident with the axis of said cylindrical body; shaft means extending through said first and second apertures; sixth fastener means for fastening said first hemispherical body to said shaft means; seventh fastener means for fastening said second hemispherical body to said shaft means; first ring housing means fastened to said shaft means in the vicinity of said first aperture and outside of said first hemispherical body for supporting filament material; second ring means for supporting filament material; and lock means attaching the said second ring means to said shaft means outside of said second hemispherical body in the vicinity of said second aperture.

2. Apparatus according to claim 1 wherein said lock means comprises a shoulder supported by said shaft means; support means for supporting said second ring housing; and eighth fastener means for clamping said support means against said shoulder means. 

1. A mandrel assembly for supporting filament material for constructing a container, said assembly comprising: a plurality of first mandrel segments each having a surface forming a portion of a substantially cylindrical body; first fastener means for fastening said first mandrel segments together to form a substantially cylindrical body; a plurality of second mandrel segments each having a surface forming a portion of a substantially hemispherical body; second fastener means for fastening said second mandrel segments together to form a first substantially hemispherical body; a plurality of third mandrel segments each having a surface forming a portion of a substantially hemispherical body; third fastener means for fastening said third mandrel segments together to form a second substantially hemispherical body; fourth fastener means for fastening said first hemispherical body to said cylindrical body; fifth fastener means for fastening said second hemispherical body to said cylindrical body; first and second apertures formed in said first and second hemispherical bodies, respectively, said apertures being coincident with the axis of said cylindrical body; shaft means extending through said first and second apertures; sixth fastener means for fastening said first hemispherical body to said shaft means; seventh fastener means for fastening said second hemispherical body to said shaft means; first ring housing means fastened to said shaft means in the vicinity of said first aperture and outside of said first hemispherical body for supporting filament material; second ring means for supporting filament material; and lock means attaching the said second ring means to said shaft means outside of said second hemispherical body in the vicinity of said second aperture.
 2. Apparatus according to claim 1 wherein said lock means comprises a shoulder supported by said shaft means; support means for supporting said second ring housing; and eighth fastener means for clamping said support means against said shoulder means. 